The Government said yesterday it had agreed "80 to 90 per cent" of a draft EU constitution expected to be finalised tomorrow, but insisted months of further negotiation on the fine print would be needed.
Peter Hain, the minister representing the UK in a convention on the future of Europe, said the Government was still resisting several proposals, including one to ditch the national veto on limited areas of taxation and a pledge to forge a common defence policy.
"I think we are looking at 80 to 90 per cent consensus," Mr Hain said. "But on the remaining 10 per cent there are really tough issues on which we will need to negotiate in the Intergovernmental Conference [IGC]", the meeting in which the final deal must be agreed.
The former French president Valéry Giscard d'Estaing hopes to wrap up the bulk of the work of the 105-member convention he chairs tomorrow, and present it to heads of government next week.
Some nations, including Germany, Italy and possibly France, may be able to sign up to the entire package, placing Britain and other sceptical countries under pressure. When EU leaders meet next week in Greece they may be asked to agree, in principle, to the draft constitution's institutional changes, including plans to create a president or chairman of the European Council.
While that may be possible for the UK, Mr Hain's warning of the need for further, detailed talks on the constitution was repeated by Jack Straw, the Foreign Secretary. He said M. Giscard's text was "a good starting point for the lengthy negotiations in the IGC".
Spain is also unlikely to accept the entire draft treaty unless M. Giscard backs away from his plan to alter a deal, struck in Nice in 2000, on voting weights for member states. Several nations also have problems with the draft's preamble, because it does not contain a reference to Christianity. Small nations, meanwhile, worry that they will lose influence, and that the European Commission, traditionally seen as their guardian, will be diminished.
Reijo Kemppinen, the chief spokesman of the European Commission, attacked recent "polarisation" and "national concerns" within the convention and quoted one unidentified commissioner as saying the latest proposals would reduce the European Commission to "a college of eunuchs".
Although Britain welcomed an apparent retreat on plans to abolish the veto on social security and employment policy, it is worried by a clause that would allow the EU member states to do away with national vetoes at any time if they agreed unanimously to do so.
Mr Straw said: "The current draft constitutional treaty shows that we are making progress towards our kind of Europe: a union of nations, not a superstate."